Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already mark it readOnly, idempotent, and non-destructive. The description adds valuable behavioral context beyond that: it specifies the return content (plan name, caps, contact reveal usage with UTC reset on the 1st, tracked app usage vs cap). This tells the agent exactly what to expect without any side effects. No contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single sentence that front-loads the purpose ('Your AffiliateSpy plan and usage') and packs in all relevant details without redundancy. Every clause earns its place, and it is immediately scannable.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a parameterless read-only tool with no output schema, the description fully covers what the agent needs: it enumerates the returned fields and even notes the reset schedule. There is no missing information that would hinder correct invocation or interpretation of the response.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, so the baseline is 4 per the rubric. There is nothing to explain beyond the schema, which is already empty. The description doesn't need to add parameter meaning, and it doesn't. This is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the resource (AffiliateSpy account) and the specific data returned: plan name, caps, contact reveal usage with reset schedule, and tracked app usage. This distinguishes it from sibling get_* tools, which all target different resources (campaign, creator, thread, etc.). No ambiguity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

While no explicit 'use when' guidance is provided, the description makes it self-evident that this is the tool to check plan limits and quota usage. It names the exact metrics (contact reveals used/left, tracked apps used vs cap), which implies it should be consulted before quota-consuming operations. It doesn't state exclusions or alternatives, but there is no competing sibling for account-level info, so this is adequate.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.